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he HTML5 specification not only embraces the past, by supporting traditional HTML- and XHTML-style syntax, but also adds a wide range of new features Although HTML5 moves forward from HTML 4, it also is somewhat of a retreat and an admission that trying to get every Web developer on the Internet to write their markup properly is a futile effort, particularly because few Web developers are actually formally trained in the technology HTML5 tries to bring order to chaos by codifying common practices, embracing what is already implemented in browsers, and documenting how these user agents (browsers or other programs that consume Web pages) should deal with our imperfect markup HTML5 s goals are grand The specification is sprawling and often misunderstood Given the confusion, the goals of this chapter are not only to summarize what is new about HTML5 and provide a roadmap to the element reference that follows, but to also expose some of the myths and misconceptions about this exciting new approach to markup

For all practical purposes, all that is different from standard HTML in this example is the <!DOCTYPE> statement Given such minimal changes, of course, basic HTML5 will immediately render correctly in browsers, as demonstrated in Figure 2-1 As indicated by its atypical <!DOCTYPE> statement, HTML5 is not defined as an SGML or XML application Because of the non-SGML/XML basis for HTML, there is no concept of validation in HTML5; instead, an HTML5 document is checked for conformance to the specification, which provides the same practical value as validation So the lack of a formal DTD is somewhat moot As an example, consider the following flawed markup:

When checked with an HTML5 conformance checker, such as the W3C Markup Validation Service used in this chapter (available at http://validatorw3org), you see the expected result:

PART I

Later, with errors corrected, a clean check is possible:

Part I:

Core Markup

NOTE Given the currently fluid nature of HTML5, developers are warned that, at least for now,

HTML5 conformance may be a bit of a moving target If you are wondering what mode the browser enters into because of the divergent

<!DOCTYPE> used by HTML5, apparently it is the more standards-oriented mode:

Employing the more standards-oriented parsing mode might seem appropriate, but it is somewhat odd given the point of the next section

Loose Syntax Returns

An interesting aspect of HTML5 is the degree of syntax variability that it allows Unlike its stricter markup cousin, XHTML, the traditional looseness of HTML is allowed To demonstrate, in the following example, quotes are not always employed, major elements like html, head, and body are simply not included, the inference of close of tags like </p> and </li> is allowed, case is used variably, and even XML-style self-identifying close syntax is used at will: